An Essay Concerning Human Understanding, by John Locke

Chapter XV

Ideas of Duration and Expansion, considered together

1. Both capable of greater and less. Though we have in the precedent chapters dwelt pretty
long on the considerations of space and duration, yet, they being ideas of general concernment, that have something
very abstruse and peculiar in their nature, the comparing them one with another may perhaps be of use for their
illustration; and we may have the more clear and distinct conception of them by taking a view of them together.
Distance or space, in its simple abstract conception, to avoid confusion, I call expansion, to distinguish it from
extension, which by some is used to express this distance only as it is in the solid parts of matter, and so includes,
or at least intimates, the idea of body: whereas the idea of pure distance includes no such thing. I prefer also the
word expansion to space, because space is often applied to distance of fleeting successive parts, which never exist
together, as well as to those which are permanent. In both these (viz. expansion and duration) the mind has this common
idea of continued lengths, capable of greater or less quantities. For a man has as clear an idea of the difference of
the length of an hour and a day, as of an inch and a foot.

2. Expansion not bounded by matter. The mind, having got the idea of the length of any
part of expansion, let it be a span, or a pace, or what length you will, can, as has been said, repeat that idea, and
so, adding it to the former, enlarge its idea of length, and make it equal to two spans, or two paces; and so, as often
as it will, till it equals the distance of any parts of the earth one from another, and increase thus till it amounts
to the distance of the sun or remotest star. By such a progression as this, setting out from the place where it is, or
any other place, it can proceed and pass beyond all those lengths, and find nothing to stop its going on, either in or
without body. It is true, we can easily in our thoughts come to the end of solid extension; the extremity and bounds of
all body we have no difficulty to arrive at: but when the mind is there, it finds nothing to hinder its progress into
this endless expansion; of that it can neither find nor conceive any end. Nor let any one say, that beyond the bounds
of body, there is nothing at all; unless he will confine God within the limits of matter. Solomon, whose understanding
was filled and enlarged with wisdom, seems to have other thoughts when he says, “Heaven, and the heaven of heavens,
cannot contain thee.” And he, I think, very much magnifies to himself the capacity of his own understanding, who
persuades himself that he can extend his thoughts further than God exists, or imagine any expansion where He is
not.

3. Nor duration by motion. Just so is it in duration. The mind having got the idea of any
length of duration, can double, multiply, and enlarge it, not only beyond its own, but beyond the existence of all
corporeal beings, and all the measures of time, taken from the great bodies of all the world and their motions. But yet
every one easily admits, that, though we make duration boundless, as certainly it is, we cannot yet extend it beyond
all being. God, every one easily allows, fills eternity; and it is hard to find a reason why any one should doubt that
He likewise fills immensity. His infinite being is certainly as boundless one way as another; and methinks it ascribes
a little too much to matter to say, where there is no body, there is nothing.

4. Why men more easily admit infinite duration than infinite expansion. Hence I think we
may learn the reason why every one familiarly and without the least hesitation speaks of and supposes Eternity, and
sticks not to ascribe infinity to duration; but it is with more doubting and reserve that many admit or suppose the
infinity of space. The reason whereof seems to me to be this — That duration and extension being used as names of
affections belonging to other beings, we easily conceive in God infinite duration, and we cannot avoid doing so: but,
not attributing to Him extension, but only to matter, which is finite, we are apter to doubt of the existence of
expansion without matter; of which alone we commonly suppose it an attribute. And, therefore, when men pursue their
thoughts of space, they are apt to stop at the confines of body: as if space were there at an end too, and reached no
further. Or if their ideas, upon consideration, carry them further, yet they term what is beyond the limits of the
universe, imaginary space: as if it were nothing, because there is no body existing in it. Whereas duration, antecedent
to all body, and to the motions which it is measured by, they never term imaginary: because it is never supposed void
of some other real existence. And if the names of things may at all direct our thoughts towards the original of men’s
ideas, (as I am apt to think they may very much,) one may have occasion to think by the name duration, that the
continuation of existence, with a kind of resistance to any destructive force, and the continuation of solidity (which
is apt to be confounded with, and if we will look into the minute anatomical parts of matter, is little different from,
hardness) were thought to have some analogy, and gave occasion to words so near of kin as durare and durum esse. And
that durare is applied to the idea of hardness, as well as that of existence, we see in Horace, Epod. xvi. ferro
duravit secula. But, be that as it will, this is certain, that whoever pursues his own thoughts, will find them
sometimes launch out beyond the extent of body, into the infinity of space or expansion; the idea whereof is distinct
and separate from body and all other things: which may, (to those who please), be a subject of further meditation.

5. Time to duration is as place to expansion. Time in general is to duration as place to
expansion. They are so much of those boundless oceans of eternity and immensity as is set out and distinguished from
the rest, as it were by landmarks; and so are made use of to denote the position of finite real beings, in respect one
to another, in those uniform infinite oceans of duration and space. These, rightly considered, are only ideas of
determinate distances from certain known points, fixed in distinguishable sensible things, and supposed to keep the
same distance one from another. From such points fixed in sensible beings we reckon, and from them we measure our
portions of those infinite quantities; which, so considered, are that which we call time and place. For duration and
space being in themselves uniform and boundless, the order and position of things, without such known settled points,
would be lost in them; and all things would lie jumbled in an incurable confusion.

6. Time and place are taken for so much of either as are set out by the existence and motion of
bodies. Time and place, taken thus for determinate distinguishable portions of those infinite abysses of space
and duration, set out or supposed to be distinguished from the rest, by marks and known boundaries, have each of them a
twofold acceptation.

First, Time in general is commonly taken for so much of infinite duration as is measured by, and co-existent with,
the existence and motions of the great bodies of the universe, as far as we know anything of them: and in this sense
time begins and ends with the frame of this sensible world, as in these phrases before mentioned, “Before all time,”
or, “When time shall be no more.” Place likewise is taken sometimes for that portion of infinite space which is
possessed by and comprehended within the material world; and is thereby distinguished from the rest of expansion;
though this may be more properly called extension than place. Within these two are confined, and by the observable
parts of them are measured and determined, the particular time or duration, and the particular extension and place, of
all corporeal beings.

7. Sometimes for so much of either as we design by measures taken from the bulk or motion of
bodies. Secondly, sometimes the word time is used in a larger sense, and is applied to parts of that infinite
duration, not that were really distinguished and measured out by this real existence, and periodical motions of bodies,
that were appointed from the beginning to be for signs and for seasons and for days and years, and are accordingly our
measures of time; but such other portions too of that infinite uniform duration, which we upon any occasion do suppose
equal to certain lengths of measured time; and so consider them as bounded and determined. For, if we should suppose
the creation, or fall of the angels, was at the beginning of the Julian period, we should speak properly enough, and
should be understood if we said, it is a longer time since the creation of angels than the creation of the world, by
7640 years: whereby we would mark out so much of that undistinguished duration as we suppose equal to, and would have
admitted, 7640 annual revolutions of the sun, moving at the rate it now does. And thus likewise we sometimes speak of
place, distance, or bulk, in the great inane, beyond the confines of the world, when we consider so much of that space
as is equal to, or capable to receive, a body of any assigned dimensions, as a cubic foot; or do suppose a point in it,
at such a certain distance from any part of the universe.

8. They belong to all finite beings. Where and when are questions belonging to all finite
existences, and are by us always reckoned from some known parts of this sensible world, and from some certain epochs
marked out to us by the motions observable in it. Without some such fixed parts or periods, the order of things would
be lost, to our finite understandings, in the boundless invariable oceans of duration and expansion, which comprehend
in them all finite beings, and in their full extent belong only to the Deity. And therefore we are not to wonder that
we comprehend them not, and do so often find our thoughts at a loss, when we would consider them, either abstractly in
themselves, or as any way attributed to the first incomprehensible Being. But when applied to any particular finite
beings, the extension of any body is so much of that infinite space as the bulk of the body takes up. And place is the
position of any body, when considered at a certain distance from some other. As the idea of the particular duration of
anything is, an idea of that portion of infinite duration which passes during the existence of that thing; so the time
when the thing existed is, the idea of that space of duration which passed between some known and fixed period of
duration, and the being of that thing. One shows the distance of the extremities of the bulk or existence of the same
thing, as that it is a foot square, or lasted two years; the other shows the distance of it in place, or existence from
other fixed points of space or duration, as that it was in the middle of Lincoln’s Inn Fields, or the first degree of
Taurus, and in the year of our Lord 1671, or the 1000th year of the Julian period. All which distances we measure by
preconceived ideas of certain lengths of space and duration — as inches, feet, miles, and degrees, and in the other,
minutes, days, and years, &c.

9. All the parts of extension are extension, and all the parts of duration are duration.
There is one thing more wherein space and duration have a great conformity, and that is, though they are justly
reckoned amongst our simple ideas, yet none of the distinct ideas we have of either is without all manner of
composition: it is the very nature of both of them to consist of parts: but their parts being all of the same kind, and
without the mixture of any other idea, hinder them not from having a place amongst simple ideas. Could the mind, as in
number, come to so small a part of extension or duration as excluded divisibility, that would be, as it were, the
indivisible unit or idea; by repetition of which, it would make its more enlarged ideas of extension and duration. But,
since the mind is not able to frame an idea of any space without parts, instead thereof it makes use of the common
measures, which, by familiar use in each country, have imprinted themselves on the memory (as inches and feet; or
cubits and parasangs; and so seconds, minutes, hours, days, and years in duration); — the mind makes use, I say, of
such ideas as these, as simple ones: and these are the component parts of larger ideas, which the mind upon occasion
makes by the addition of such known lengths which it is acquainted with. On the other side, the ordinary smallest
measure we have of either is looked on as an unit in number, when the mind by division would reduce them into less
fractions. Though on both sides, both in addition and division, either of space or duration, when the idea under
consideration becomes very big or very small its precise bulk becomes very obscure and confused; and it is the number
of its repeated additions or divisions that alone remains clear and distinct; as will easily appear to any one who will
let his thoughts loose in the vast expansion of space, or divisibility of matter. Every part of duration is duration
too; and every part of extension is extension, both of them capable of addition or division in infinitum. But the least
portions of either of them, whereof we have clear and distinct ideas, may perhaps be fittest to be considered by us, as
the simple ideas of that kind out of which our complex modes of space, extension, and duration are made up, and into
which they can again be distinctly resolved. Such a small part in duration may be called a moment, and is the time of
one idea in our minds, in the train of their ordinary succession there. The other, wanting a proper name, I know not
whether I may be allowed to call a sensible point, meaning thereby the least particle of matter or space we can
discern, which is ordinarily about a minute, and to the sharpest eyes seldom less than thirty seconds of a circle,
whereof the eye is the centre.

10. Their parts inseparable. Expansion and duration have this further agreement, that,
though they are both considered by us as having parts, yet their parts are not separable one from another, no not even
in thought: though the parts of bodies from whence we take our measure of the one; and the parts of motion, or rather
the succession of ideas in our minds, from whence we take the measure of the other, may be interrupted and separated;
as the one is often by rest, and the other is by sleep, which we call rest too.

11. Duration is as a line, expansion as a solid. But there is this manifest difference
between them — That the ideas of length which we have of expansion are turned every way, and so make figure, and
breadth, and thickness; but duration is but as it were the length of one straight line, extended in infinitum, not
capable of multiplicity, variation, or figure; but is one common measure of all existence whatsoever, wherein all
things, whilst they exist, equally partake. For this present moment is common to all things that are now in being, and
equally comprehends that part of their existence, as much as if they were all but one single being; and we may truly
say, they all exist in the same moment of time. Whether angels and spirits have any analogy to this, in respect to
expansion, is beyond my comprehension: and perhaps for us, who have understandings and comprehensions suited to our own
preservation, and the ends of our own being, but not to the reality and extent of all other beings, it is near as hard
to conceive any existence, or to have an idea of any real being, with a perfect negation of all manner of expansion, as
it is to have the idea of any real existence with a perfect negation of all manner of duration. And therefore, what
spirits have to do with space, or how they communicate in it, we know not. All that we know is, that bodies do each
singly possess its proper portion of it, according to the extent of solid parts; and thereby exclude all other bodies
from having any share in that particular portion of space, whilst it remains there.

12. Duration has never two parts together, expansion altogether. Duration, and time which
is a part of it, is the idea we have of perishing distance, of which no two parts exist together, but follow each other
in succession; an expansion is the idea of lasting distance, all whose parts exist together, and are not capable of
succession. And therefore, though we cannot conceive any duration without succession, nor can put it together in our
thoughts that any being does now exist tomorrow, or possess at once more than the present moment of duration; yet we
can conceive the eternal duration of the Almighty far different from that of man, or any other finite being. Because
man comprehends not in his knowledge or power all past and future things: his thoughts are but of yesterday, and he
knows not what tomorrow will bring forth. What is once past he can never recall; and what is yet to come he cannot make
present. What I say of man, I say of all finite beings; who, though they may far exceed man in knowledge and power, yet
are no more than the meanest creature, in comparison with God himself Finite or any magnitude holds not any proportion
to infinite. God’s infinite duration, being accompanied with infinite knowledge and infinite power, He sees all things,
past and to come; and they are no more distant from His knowledge, no further removed from His sight, than the present:
they all lie under the same view: and there is nothing which He cannot make exist each moment He pleases. For the
existence of all things, depending upon His good pleasure, all things exist every moment that He thinks fit to have
them exist. To conclude: expansion and duration do mutually embrace and comprehend each other; every part of space
being in every part of duration, and every part of duration in every part of expansion. Such a combination of two
distinct ideas is, I suppose, scarce to be found in all that great variety we do or can conceive, and may afford matter
to further speculation.